407] FLORA OF BOULDER, COLORADO 259 



1219. L. integrata (Gren. & Goclr.) A. Nels. [L. virosa 

 Auct., not L.] Prickly lettuce. 



Common in waste places, 5100-6000 ft. (Daniels, 653). 

 Europe, thence to North America. 



1220. L. Canadensis L. Common wild lettuce. 



Boulder Cafion, and along other streams in the foothills, 

 6000-7000 ft. (Daniels, 564). 



Nova Scotia to Saskatchewan ; Florida to Colorado. 



1221. L. Ludoviciana (Nutt.) DC. Louisiana lettuce. 

 Between Sunshine and Ward (Rydberg). 



North Carolina to Missouri and Colorado and Texas. 



1222. L. pulchella (Pursh) DC. Showy lettuce. 

 Plains about Boulder, 5100-6000 ft. (Daniels, 399). 

 Saskatchewan to Washington ; Missouri to California. 



1223. L. spicata (Lam.) Hitchc. [L. leucophaea Gray]. 

 Common blue lettuce. 



Sunset Cafion, 6300 ft. (Daniels, 982). Also Boulder (Ryd- 

 berg). 



Newfoundland to Manitoba ; North Carolina to Colo- 

 rado. 



486. SONCHUS L. Sow-thistle. 



1224. S. arvensis L. Field sow-thistle. 



Waste places in Boulder, 5300-5600 ft. (Daniels, 1036). 

 Europe, thence to North America. 



1225. S. asper (L.) Hill. Harsh sow-thistle. 



Boulder Caiion road, and Gregory Cafion road, 5600-6000 ft. 

 (Daniels, 458). 

 Europe, thence to North America. 



